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Topic: Digital I/O Recall (Read 2801 times) previous topic - next topic

buildafriend

Hi  :)

I want to make a box with 50 inputs and 50 outputs that essentially operate as independent non directional "thru" paths that can handle up to 30 volts RMS p2p, like a simple set of wires but reconfigurable digitally. No relays.

The interface must work on rotary encoders that matches "ports" in any configuration the user wants that are viewable on a screen. These configurations must be recallable at the push of a button.

example:
1 to 51
2 to 52
9 to 99

There is more to this idea, but this is my starting point. Help an Arduino newb? I have a background in component level tech work, but not in digital electronics. I'm pretty good with analog circuitry :)

Cheers,

It's not a matter of what can or can't be accomplished. It's a matter of how much time you have in conjunction with your willingness, and budget.

Grumpy_Mike

#1
Oct 23, 2018, 06:54 pm Last Edit: Oct 23, 2018, 06:57 pm by Grumpy_Mike
Quote
operate as independent non directional "thru" paths that can handle up to 30 volts RMS p2p, like a simple set of wires but reconfigurable digitally.
So 30V RMS is +42V and -42V or 84V peak to peak.

This is not a beginners project and I feel it is way too big for you. What sort of current do you want to switch? That is often a big crunch. Most electronics will not run at these sorts of voltages, you are in expensive territory.
I would certainly not try and build such a system myself.

Basically this sort of things is called a Crossbar switch and would cost you several thousands of $ to make.

Imagine if you could get a switch element for $1, a highly unlikely prospect, then the project would cost you at least $2500.

Paul__B

Perhaps you should solve the "XY problem" here first.

buildafriend

#3
Oct 23, 2018, 11:56 pm Last Edit: Oct 24, 2018, 12:02 am by buildafriend
So 30V RMS is +42V and -42V or 84V peak to peak.

This is not a beginners project and I feel it is way too big for you. What sort of current do you want to switch? That is often a big crunch. Most electronics will not run at these sorts of voltages, you are in expensive territory.
I would certainly not try and build such a system myself.

Basically this sort of things is called a Crossbar switch and would cost you several thousands of $ to make.

Imagine if you could get a switch element for $1, a highly unlikely prospect, then the project would cost you at least $2500.
RMS is just 0.707 times whatever the other p2p is... 42 sounds right depending on where the starting point was. Who said we were starting with only the up or down cycle? Thanks for taking the time to do that though. I mean 42VAC p2p if thats easier for you.

There are no digital switching chips that can handle 30V? low current, milli amps..

We're talking about switching audio here.. synthesizers that max out at 10 V.. the 30 is a precaution to help with spikes. Lots of companies seem to be making digital switching matrixes.

Lets have a look at that beginners XY problem : )




It's not a matter of what can or can't be accomplished. It's a matter of how much time you have in conjunction with your willingness, and budget.

buildafriend

#4
Oct 24, 2018, 12:01 am Last Edit: Oct 24, 2018, 12:44 am by buildafriend
I think your XY problem is mainly negative thinking in this case.

Can anyone point me in the direction of a project that does some simple port switching?
It's not a matter of what can or can't be accomplished. It's a matter of how much time you have in conjunction with your willingness, and budget.

Delta_G

#5
Oct 24, 2018, 01:43 am Last Edit: Oct 24, 2018, 01:44 am by Delta_G
We're talking about switching audio here.. synthesizers that max out at 10 V.. the 30 is a precaution to help with spikes. Lots of companies seem to be making digital switching matrixes.

Any other details you left out of the OP? 

Want real help and not the runaround?  There are many of us who can help, just waiting for you to fill in all the details.  But I'm not going to get into the scrum trying to figure out what you're building.  Just come out with it or keep dealing with what you're getting.  Be detailed and you'll get better help from different folks.  Keep it vague and you'll just get what you're getting. 
|| | ||| | || | ||  ~Woodstock

Please do not PM with technical questions or comments.  Keep Arduino stuff out on the boards where it belongs.

Grumpy_Mike

#6
Oct 24, 2018, 08:08 am Last Edit: Oct 24, 2018, 08:10 am by Grumpy_Mike
Quote
I mean 42VAC p2p if thats easier for you.
No that is 42V peak, it would be 84V peak to peak.

Quote
42 sounds right depending on where the starting point was. Who said we were starting with only the up or down cycle?
That is just a nonsense. What is a starting point? Do you know any AC theory?

Quote
There are no digital switching chips that can handle 30V? low current, milli amps..
As we have established you need more than that, and this is the first time you have mentioned low current, even analogue switches at 30V are quite rare and expensive things.

Quote
We're talking about switching audio here.. synthesizers that max out at 10 V.
Nice of you to let us know.


Quote
the 30 is a precaution to help with spikes.
That is rubbish. You are backing off quite a bit from what you initially said.

We can only go off the information you provide we do not read minds.

Quote
Lots of companies seem to be making digital switching matrixes.
If you can find a 50 by 50 crossbar switch I would be happy to look at the link and tell you why this is different from what you asked for.

So this is an X-Y problem after all.

buildafriend

#7
Oct 25, 2018, 04:57 am Last Edit: Oct 25, 2018, 05:34 am by buildafriend
Im not here to get technical about your advice Mike :)

What details seem missing to you? I'll explain whatever else you need!
It's not a matter of what can or can't be accomplished. It's a matter of how much time you have in conjunction with your willingness, and budget.

Delta_G

#8
Oct 25, 2018, 06:27 am Last Edit: Oct 25, 2018, 06:33 am by Delta_G
What details seem missing to you? I'll explain whatever else you need!
No, you explain everything.  I don't want to have to try to guess at anything.  I don't want to have to go through a process of asking a bunch of question to try to figure out what you are doing.  Either just explain the whole thing in detail or keep dealing with Mike.  Give me enough detail that I could build one just like it here if I wanted exactly like what you want and test it and get exactly the same results. 

Start by telling me what it is supposed to do.  Not technical, no "hook this signal to that blah blah.  Tell me what it is supposed to do, this thing will take sounds from my trumpet and play them on a drum machine.  I hope I can accomplish this by...  EXACTLY what signals you have and where they come from.  Things like that.  I don't want to waste time on someone vaguely half-assed explaining and then once I've put in some effort suddenly there's one more requirement or whatever.  Just get it ALL out there. 
|| | ||| | || | ||  ~Woodstock

Please do not PM with technical questions or comments.  Keep Arduino stuff out on the boards where it belongs.

Grumpy_Mike

#9
Oct 25, 2018, 07:32 am Last Edit: Oct 25, 2018, 07:35 am by Grumpy_Mike
Im not here to get technical about your advice
Maybe, but this technicality is very important, it determines if your project is at all feasible.
We started with a requirement to switch 30V RMS, which I said translates into an 82V Peak to Peak signal. That sort of thing is very difficult to do. It turns out you actually want to a 10V AC signal but we have not established if the 10V is RMS, Peak or Peak to Peak. Any electronic switch has to be able to cope with the Peak to Peak value of the voltage you are going to switch. Talk of wanting an overhead to handle spikes is just a nonsense.

Next is the size of this cross bar switch a 50 by 50 matrix is very big. It means you have to generate 2500 output signals, one to drive each of the switches. That in itself is a major project. Suppose you can get a chip that will expand the outputs to give you 16 extra pins, then you will need 157 of such chips.

Then you have the signal switches themselves. I might have found a IC switch that would switch +/- 15V, it contains 4 switches, so that means you need 625 of them. So already your system has 782 ICs, I don't think this is feasible, so is it possible to reduce the size of your system?

Delta_G is spot on, we need to know a lot more about your needs rather than your wants and we need to know what is feeding this signals and where they are going to. You said:-
Quote
There is more to this idea, but this is my starting point
We need to know what this is because this could be a dead end. It is clear that the present requirements are way over the top in terms of practicality and also budget. Do you have a budget? What is it?

Paul__B

Brief research indicates he had the same problem last project.  :smiley-eek:


buildafriend

#11
Oct 25, 2018, 05:15 pm Last Edit: Oct 25, 2018, 05:35 pm by buildafriend
Okay I'll put this as simple as possible. I'm trying to make a device that memorizes synth patches similar to the device below but one that can handle much more I/O than that. As for the how the device works TBH I really don't care as long as I can build it, make it open source, and it's a user friendly device for the operator/musician can use for patching and recall. Do you want me to design a front panel so we can work from the front panel down?

I simply figured it would be nice to have more power handling. If that's prohibitive lets forget it and stick with whatever does the job. 

Mike is right about RMS. I needed to glance back over that one.

Similar to this - but more I/O. Lets forget making it any more complicated than that for now.

https://www.ericasynths.lv/shop/eurorack-modules/by-series/basic-series/matrix-mixer/

Input signal level

up to 20 Vptp

Inputs

10

Outputs

8

Signal mode

both audio and CV

Mixer GAIN

1

Resistive touchscreen

3,2"

Internal clock

20-320 BPM

Power supply

bipolar +-12V , eurorack standard

Does anything still feel vague?
It's not a matter of what can or can't be accomplished. It's a matter of how much time you have in conjunction with your willingness, and budget.

buildafriend

#12
Oct 25, 2018, 05:22 pm Last Edit: Oct 25, 2018, 05:25 pm by buildafriend
Start by telling me what it is supposed to do.  Not technical, no "hook this signal to that blah blah.  Tell me what it is supposed to do, this thing will take sounds from my trumpet and play them on a drum machine.  I hope I can accomplish this by...  EXACTLY what signals you have and where they come from.  Things like that.  I don't want to waste time on someone vaguely half-assed explaining and then once I've put in some effort suddenly there's one more requirement or whatever.  Just get it ALL out there. 
Does my above post help with this?

see this pic? at the top of this page?
http://www.electronicbeats.net/the-feed/eurorack-modular-synth-laptop-free/

I want to make all of that wiring go to one box that is control unit for patching it all.

Here is an archaic version
http://www.vintagesynth.com/misc/synthi.php
It's not a matter of what can or can't be accomplished. It's a matter of how much time you have in conjunction with your willingness, and budget.

Grumpy_Mike

Quote
Similar to this - but more I/O. Lets forget making it any more complicated than that for now.
https://www.ericasynths.lv/shop/eurorack-modules/by-series/basic-series/matrix-mixer/
So how much more I/O? The complexity and the price goes up as the number of inputs times the number outputs increases. That link shows an out of stock product but a web search shows this "small" cross bar switch as costing €447. Are you expecting to be able to recreate a one off of this than less than that?

Quote
http://www.electronicbeats.net/the-feed/eurorack-modular-synth-laptop-free/
I want to make all of that wiring go to one box that is control unit for patching it all.
No way Jose.

What you are fighting here is that:-
1) They have made many prototypes
2) It has been tested and worked on by experts, my guess is that it would have taken about 5 man years to develop and bring to market.
3) They have the ability to buy components in bulk at a fraction of the price that you can.

It is a very ambitious project just to replicate what they have done, let alone take it further. As I asked, what is your budget?

I think asking someone to design it for you is an impossible ask.

You might want to look more at the open synth forums and ask about this there.

Good luck with your project.

buildafriend

#14
Oct 25, 2018, 08:07 pm Last Edit: Oct 25, 2018, 08:10 pm by buildafriend
Let's say budget is 2k for prototyping.

Target is 50 in and 50 out.. but that's a little flexible.

Do we all agree that a crossbar topology is a good solution?
It's not a matter of what can or can't be accomplished. It's a matter of how much time you have in conjunction with your willingness, and budget.

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